1. Technical Field
The present invention relates to the field of moisture-curing compositions, in particular the field of moisture-curing polymers containing silane functional groups (silane-functional polymers).
2. Prior Art
Moisture-curing compositions based on silane-functional polymers are known in the prior art, and are used inter alia as elastic adhesives, sealants, and coatings. They do not contain isocyanate groups and therefore from a toxicological viewpoint are preferred alternatives to isocyanate-containing polyurethane systems.
WO 03/018658 A1 describes silane-functional polymers with α-functional silane groups as end groups, which are distinguished by high reactivity and thus faster curing. WO 2007/085620 A1 also describes the use of silane-functional polymers with α-functional silane groups as end groups in adhesives and sealants having improved adhesion. However, such systems have a considerable tendency toward creep.
U.S. Pat. No. 3,971,751 and U.S. Pat. No. 6,207,766 describe silane-terminated polyether polymers which can be used in moisture-curing compositions. However, such systems firstly are very slow curing and sometimes possibly have a tendency toward creep. US 2006/0128919 A1 discloses that creep of such silane-terminated polyether polymers can be improved by addition of silicates or tin catalysts. Tin catalysts, however, are often undesirable for ecological and occupational safety reasons.
For example, U.S. Pat. No. 5,364,955 discloses compositions which contain silane-terminated polyurethane polymers. Development of adhesion in such systems, however, is very slow.
WO 2007/085622 A1 discloses in an Example an adhesive which, in addition to a polymer with α-functional silane groups, contains an extremely small amount of acrylate polymer with silane groups. However, this system tends toward creep. US 2007/0088137 discloses sprayable adhesives which contain a phenol resin as a tackifier and a polymer with hydrolyzable silicon end groups. The Examples of that patent include sprayable adhesives which, in addition to a phenol resin as a tackifier, also contain a dimethoxy(methyl)silylmethylcarbamate-terminated polyether as well as other silane-terminated polymers if needed.
WO 2006/130592 A1 discloses a polyurethane sealant which consists essentially of an isocyanate-terminated polyurethane prepolymer and only small amounts of a polymer with α-functional silane groups and an even smaller amount of a silane-terminated polyurethane polymer. Such sealants, however, have large amounts of isocyanate groups and are therefore undesirable from a toxicological standpoint.